In image sensors, three dimensional information of an image is desired to be determined. For example, respective distances to points of a target are determined for forming a three dimensional image of the target or for other three dimensional image processing.
Such three dimensional information may be used for three dimensional shape measurement of the target. In the prior art, light is transmitted to the target, and one of triangulation, interferometry, or time of flight is used with light reflected from the target for determining the distances to points of the target.
In any case, a mechanism for accurately and efficiently determining the distances to points of the target is desired.